To kick off my look this week at the best prospects in the minor leagues, I've ranked all 30 MLB farm systems from top to bottom, considering only the players who are currently in the systems and have not yet exhausted their rookie year of eligibility. (I use the same criterion for the individual player rankings that will be posted over the next few days.)

There's a real concentration of talent among the top few farm systems, teams that have been bad in recent years and stockpiled prospects, plus a couple of clubs that have wielded their financial might to bolster their farms. The top few clubs can all boast a dozen or more prospects with decent chances to become average big leaguers or better, whereas at the bottom of the list, you might find only one or two such prospects per club. (My top 10 rankings by team will be released early next week.) The rankings favor teams with more of those "average big leaguer or better" prospects because of the scarcity of those players and the increasing cost of a fourth starter or just an average everyday player in free agency. Quality relievers and bench players are nice to have in your system -- it sure beats paying for them on the open market -- but they don't measure up to clubs that have lots of potential grade 50s (on the 20-80 grading scale) in their systems.

This system was among the bottom five just two years ago after several bad drafts and questionable player development, but a series of trades -- including several fleecings of the Diamondbacks -- has stocked the system with pitching depth that is the envy of the industry. They tied for the most players in my top 100 and had a couple of other players who could make cases for inclusion, and their 11th- to 20th-ranked prospects still include a lot of prospective major league value. It has been a remarkable turnaround for general manager John Coppolella and his front office, and the future is even brighter with the team having the third overall pick in June's draft. The team's agreement to sign Venezuelan prospect Kevin Maitan on July 2 is the worst-kept secret in the industry.

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